With the emphasis on sealing properties, elastic bodies, such as rubber, are used in parts that slide while maintaining a seal, such as a gasket which is integrated with a syringe plunger and forms a seal between the plunger and the barrel. Such elastic bodies, however, have a slight problem in their sliding properties (see Patent Literature 1). Therefore, a sliding property improver, such as silicone oil, is applied to the sliding surface, but it is pointed out that such silicone oil can adversely affect recently marketed bio-preparations. On the other hand, gaskets not coated with silicone oil are remarkably poor in sliding properties and therefore do not allow plungers to be smoothly pushed but cause them to pulsate during administration, resulting in problems such as inaccurate injection amounts and infliction of pain on patients.
In order to satisfy the conflicting requirements, sealing properties and sliding properties, a method of coating surfaces with a self-lubricating PTFE film has been proposed (see Patent Literature 2). Although the surfaces coated with a PTFE film achieve sufficient sliding properties, there still exists a need to further enhance sliding properties. Moreover, the PTFE film coating can sufficiently reduce adsorption of proteins contained in bio-preparations, but there remains a need for further reduction in the adsorption.
Furthermore, the use in other applications where sliding properties in the presence of water are required can be considered. Specifically, water can be delivered without a loss by reducing the fluid resistance of the inner surface of a pre-filled syringe or of the inner surface of a pipe or tube for delivering water, or by increasing or greatly reducing the contact angle with water. Also, drainage of water on wet roads and of snow on snowy roads can be improved by reducing the fluid resistance of the groove surfaces of tires, or by increasing or greatly reducing the contact angle with water. This results in enhanced grip performance, and therefore better safety. In addition, less adhesion of wastes and dusts can be expected when the sliding resistance of the sidewall surfaces of tires or the walls of buildings is reduced, or when their contact angle with water is increased.
Further advantageous effects can be expected, including, for example: less pressure loss when water, an aqueous solution, or the like is delivered through a diaphragm such as a diaphragm pump or valve; easy sliding of skis and snowboards by enhancing the sliding properties of the sliding surfaces thereof; better noticeability of road signs and signboards by enhancing the sliding properties thereof to allow snow to slide easily; reduction in water resistance or drag and less adhesion of bacteria on the outer peripheries of ships by reducing the sliding resistance of the outer peripheries, or by increasing the contact angle with water; and reduction in water resistance or drag of swimsuits by improving the sliding properties of the thread surfaces thereof.